The present invention relates generally to anti-counterfeiting patterns on a document and, more particularly, to line patterns on the front and back surfaces of a document which allow a document holder to verify the authenticity of the document and which have enhanced security protection against copying of the document.
A great number of printed documents require highly reliable means of ensuring their authenticity. These documents include currency, negotiable instruments, stock certificates, checks, tickets and the like. The means employed to indicate authenticity for the document should be permanent, durable, and difficult to replicate to allow the public at large to rely on the authenticity of the documents. This latter quality is particularly important to preclude, or at least to dissuade attempts at counterfeiting the documents in order to ensure a maximum degree of confidence in the original document. In the case of banknotes, passports, checks, and other intrinsically valuable documents, confidence in the authenticity of the document is especially important, as any member of the public might become a holder or user of the document at any time.
The criteria for an effective document security feature are relatively easy to formulate. Such features should be difficult to replicate to deter potential counterfeiters. The features should permit ready detection by means available to ordinary holders or users of the final document. For banknotes and other documents on whose authenticity the public at large relies, the features should be discernible and verifiable under ordinary light conditions.
The increasing popularity of color photocopiers and other imaging systems, and the improving technical quality of color photocopiers, has led to an increase in the counterfeiting of such documentation.
A wide variety of security features for documents have been proposed previously. Examples of such security features include: optically variable devices, such as holograms and diffraction gratings; security threads or strips; microprint; watermarks; fine line or ‘filigree’ patterns; or color-shifting inks, fluorescent inks, and phosphorescent inks.
These measures naturally add to the complexity and production cost of the documents.
A disadvantage is that several of these document security features may require an optical filter or other external equipment, to provide the required lighting condition for verification of the security device. For example, fluorescent inks may require a source of ultraviolet light for their verification, and microprint, fine line and filigree patterns may require a magnifying lens for verification or may only be machine readable.
To prevent unauthorized duplication or alteration of documents, frequently special indicia or a background pattern are provided for document sheet materials. The indicia or background pattern is imposed upon the sheet material usually by some type of printing process such as offset printing, lithography, letterpress or other like mechanical systems, by a variety of photographic methods, by xerographic printing, and a host of other methods. Most of these patterns placed on sheet materials depend upon complexity and resolution to avoid ready duplication. Consequently, they add an increment of cost to the sheet material without being fully effective in many instances in providing the desired protection from unauthorized duplication or alteration.
It is an object of the present invention to provide a low cost, anti-counterfeiting pattern on a document which is easy to manufacture and yet difficult to counterfeit.
It is another object of the present invention to provide an anti-counterfeiting pattern on a document which a document user or holder with no additional external equipment can verify the authenticity of the document.